1 2952 43 GENETIC AND EPIGENETIC ETIOLOGY OF INFLAMMATORY BOWEL DISEASE: AN UPDATE. INFLAMMATORY BOWEL DISEASE (IBD) IS A CHRONIC DISEASE WITH PERIODS OF EXACERBATION AND REMISSION OF THE DISEASE. THE ETIOLOGY OF IBD IS NOT FULLY UNDERSTOOD. MANY STUDIES POINT TO THE PRESENCE OF GENETIC, IMMUNOLOGICAL, ENVIRONMENTAL, AND MICROBIOLOGICAL FACTORS AND THE INTERACTIONS BETWEEN THEM IN THE OCCURRENCE OF IBD. THE REVIEW LOOKS AT GENETIC FACTORS IN THE CONTEXT OF BOTH IBD PREDISPOSITION AND PHARMACOGENETICS. 2022 2 3541 20 IMMUNOEPIGENETIC REGULATION OF INFLAMMATORY BOWEL DISEASE: CURRENT INSIGHTS INTO NOVEL EPIGENETIC MODULATIONS OF THE SYSTEMIC IMMUNE RESPONSE. THE IMMUNE SYSTEM AND ENVIRONMENTAL FACTORS ARE INVOLVED IN VARIOUS DISEASES, SUCH AS INFLAMMATORY BOWEL DISEASE (IBD), THROUGH THEIR EFFECT ON GENETICS, WHICH MODULATES IMMUNE CELLS. IBD ENCOMPASSES TWO MAIN PHENOTYPES, CROHN'S DISEASE, AND ULCERATIVE COLITIS, WHICH ARE MANIFESTED AS CHRONIC AND SYSTEMIC RELAPSE-REMITTING GASTROINTESTINAL TRACT DISORDERS WITH RISING GLOBAL INCIDENCE AND PREVALENCE. THE PATHOPHYSIOLOGY OF IBD IS COMPLEX AND NOT FULLY UNDERSTOOD. EPIGENETIC RESEARCH HAS RESULTED IN VALUABLE INFORMATION FOR UNRAVELING THE ETIOLOGY OF THIS IMMUNE-MEDIATED DISEASE. THUS, THE MAIN OBJECTIVE OF THE PRESENT REVIEW IS TO SUMMARIZE THE CURRENT FINDINGS ON THE ROLE OF EPIGENETIC MECHANISMS IN IBD TO SHED LIGHT ON THEIR POTENTIAL CLINICAL RELEVANCE. THIS REVIEW FOCUSES ON THE LATEST EVIDENCE REGARDING PERIPHERAL BLOOD MONONUCLEAR CELLS AND EPIGENETIC CHANGES IN HISTONE MODIFICATION, DNA METHYLATION, AND TELOMERE SHORTENING IN IBD. THE VARIOUS IDENTIFIED EPIGENETIC DNA PROFILES WITH CLINICAL VALUE IN IBD COULD BE USED AS BIOMARKERS FOR MORE ACCURATELY PREDICTING DISEASE DEVELOPMENT, TREATMENT RESPONSE, AND THERAPY-RELATED ADVERSE EVENTS. ULTIMATELY, THE INFORMATION PRESENTED HERE COULD BE OF POTENTIAL RELEVANCE FOR FUTURE CLINICAL PRACTICE IN DEVELOPING MORE EFFICIENT AND PRECISE MEDICINE TO IMPROVE THE QUALITY OF LIFE FOR PATIENTS WITH IBD. 2023 3 2675 19 ETIOPATHOGENESIS OF INFLAMMATORY BOWEL DISEASE: TODAY AND TOMORROW. PURPOSE OF REVIEW: CROHN'S DISEASE AND ULCERATIVE COLITIS, THE TWO MAJOR FORMS OF INFLAMMATORY BOWEL DISEASE (IBD), REPRESENT CHRONIC DISEASES OF UNKNOWN CAUSE, AND THEY ARE REGARDED AS PROTOTYPICAL COMPLEX DISEASES. DESPITE ALL THE RECENT ADVANCES, A COMPLETE APPRECIATION OF THE PATHOGENESIS OF IBD IS STILL LIMITED. IN THIS REVIEW, WE PRESENT RECENT INFORMATION CONTRIBUTING TO A BETTER UNDERSTANDING OF MECHANISMS UNDERLYING IBD. RECENT FINDINGS: HERE, WE ATTEMPT TO HIGHLIGHT NOVEL ENVIRONMENTAL TRIGGERS, DATA ON THE GUT MICROBIOTA, ITS INTERACTION WITH THE HOST, AND THE POTENTIAL INFLUENCE OF DIET AND FOOD COMPONENTS. WE DISCUSS RECENT FINDINGS ON DEFECTIVE SIGNALING PATHWAYS AND THE POTENTIAL EFFECTS ON THE IMMUNE RESPONSE, AND WE PRESENT NEW DATA ON EPIGENETIC CHANGES, INFLAMMASOME, AND DAMAGE-ASSOCIATED MOLECULAR PATTERNS ASSOCIATED WITH IBD. SUMMARY: THE CONTINUING IDENTIFICATION OF SEVERAL EPIGENETIC, TRANSCRIPTOMIC, PROTEOMIC, AND METABOLOMIC ALTERATIONS IN PATIENTS WITH IBD REFLECTS THE COMPLEX NATURE OF THE DISEASE AND SUGGESTS THE NEED FOR INNOVATIVE APPROACHES SUCH AS SYSTEMS BIOLOGY FOR IDENTIFYING NOVEL RELEVANT TARGETS IN IBD. 2017 4 4670 19 NEW INSIGHTS INTO THE EPIGENETIC REGULATION OF INFLAMMATORY BOWEL DISEASE. INFLAMMATORY BOWEL DISEASE (IBD) IS A CHRONIC INFLAMMATORY DISEASE OF THE COLONIC MUCOSA. ENVIRONMENTAL FACTORS, GENETICS, INTESTINAL MICROBIOTA, AND THE IMMUNE SYSTEM ARE ALL INVOLVED IN THE PATHOPHYSIOLOGY OF IBD. LATELY, ACCUMULATING EVIDENCE HAS SHOWN THAT ABNORMAL EPIGENETIC CHANGES IN DNA METHYLATION, HISTONE MARKERS, AND NON-CODING RNA EXPRESSION GREATLY CONTRIBUTE TO THE DEVELOPMENT OF THE ENTIRE DISEASE. EPIGENETICS REGULATES MANY FUNCTIONS, SUCH AS MAINTAINING THE HOMEOSTASIS OF THE INTESTINAL EPITHELIUM AND REGULATING THE IMMUNE SYSTEM OF THE IMMUNE CELLS. IN THE PRESENT STUDY, WE SYSTEMATICALLY SUMMARIZED THE LATEST ADVANCES IN EPIGENETIC MODIFICATION OF IBD AND HOW EPIGENETICS REVEALS NEW MECHANISMS OF IBD. OUR PRESENT REVIEW PROVIDED NEW INSIGHTS INTO THE PATHOPHYSIOLOGY OF IBD. MOREOVER, EXPLORING THE PATTERNS OF DNA METHYLATION AND HISTONE MODIFICATION THROUGH EPIGENETICS CAN NOT ONLY BE USED AS BIOMARKERS OF IBD BUT ALSO AS A NEW TARGET FOR THERAPEUTIC INTERVENTION IN IBD PATIENTS. 2022 5 3017 17 GENETICS AND EPIGENETICS OF INFLAMMATORY BOWEL DISEASE. THE RELEVANCE OF GENETIC AND EPIGENETIC ALTERATIONS IN THE PATHOGENESIS OF INFLAMMATORY BOWEL DISEASE (IBD) IS STILL POORLY UNDERSTOOD. SO FAR, 240 RISK GENE LOCI HAVE BEEN ASSOCIATED WITH IBD. THEY ARE MAINLY INVOLVED IN REGULATING INNATE AND ADAPTIVE IMMUNITY, AS WELL AS MAINTAINING INTESTINAL EPITHELIAL BARRIER FUNCTION. HOWEVER, THE FUNCTIONAL CONSEQUENCES OF THE IDENTIFIED GENETIC POLYMORPHISMS FOR IBD PATHOGENESIS IN VIVO ARE OFTEN UNKNOWN. EVEN LESS IS KNOWN ABOUT THE ROLE FOR EPIGENETIC MODIFICATIONS IN IBD PATHOGENESIS. THOUGH A NUMBER OF EPIGENETIC EVENTS SEEM TO BE CAUSATIVELY INVOLVED IBD PATHOGENESIS, OUR KNOWLEDGE ABOUT THE FUNCTIONAL RELEVANCE OF THOSE EPIGENETIC MODIFICATIONS IS SCANTY. THIS OPENS UP A BROAD RESEARCH FIELD THAT GENERATES NOVEL INSIGHTS INTO THE PATHOPHYSIOLOGY OF INTESTINAL AND CHRONIC INFLAMMATORY DISEASE. PATTERNS OF DNA METHYLATION AND HISTONE MODIFICATIONS MIGHT SERVE NOT ONLY AS BIOMARKERS OF DISEASE ACTIVITY OR DISEASE COURSE, BUT ALSO AS NEW TARGETS IN THERAPEUTIC INTERVENTIONS IN IBD PATIENTS. 2018 6 3016 22 GENETICS AND EPIGENETICS OF IBD. INFLAMMATORY BOWEL DISEASES (IBD) ARE CHRONIC INTERMITTENT INFLAMMATORY DISORDERS OF THE GASTROINTESTINAL TRACT OF UNKNOWN ETIOLOGY BUT A CLEAR GENETIC PREDISPOSITION. PROMPTED BY THE FIRST INVESTIGATIONS ON IBD FAMILIES AND TWINS, THE GENETIC AND EPIGENETIC STUDIES HAVE PRODUCED AN UNPRECEDENTED AMOUNT OF INFORMATION IN COMPARISON WITH OTHER IMMUNE-MEDIATED OR COMPLEX DISEASES. NEW INFLAMMATORY PATHWAYS AND POSSIBLE MECHANISMS OF ACTION HAVE BEEN DISCLOSED, POTENTIALLY LEADING TO NEW-TARGETED THERAPY. HOWEVER, THE IDENTIFICATION OF GENETIC MARKERS DUE TO THE GREAT DISEASE HETEROGENEITY AND THE OVERWHELMING CONTRIBUTION OF ENVIRONMENTAL RISK FACTORS HAS NOT MODIFIED YET THE DISEASE MANAGEMENT. THE POSSIBILITY FOR THE FUTURE OF A BETTER PREDICTION OF DISEASE COURSE, RESPONSE TO THERAPY AND THERAPY-RELATED ADVERSE EVENTS MAY ALLOW A MORE EFFICIENT AND PERSONALIZED STRATEGY. THIS REVIEW WILL FOCUS ON MORE RECENT DISCOVERIES THAT MAY POTENTIALLY BE OF RELEVANCE IN DAILY CLINICAL PRACTICE. 2020 7 566 22 BASES FOR THE ADEQUATE DEVELOPMENT OF NUTRITIONAL RECOMMENDATIONS FOR PATIENTS WITH INFLAMMATORY BOWEL DISEASE. INFLAMMATORY BOWEL DISEASE (IBD) IS A CHRONIC AND RELAPSING INFLAMMATORY CONDITION OF THE GASTROINTESTINAL TRACT; IT IS A HETEROGENEOUS AND MULTIFACTORIAL DISORDER RESULTING FROM A COMPLEX INTERPLAY BETWEEN GENETIC VARIATION, INTESTINAL MICROBIOTA, THE HOST IMMUNE SYSTEM AND ENVIRONMENTAL FACTORS SUCH AS DIET, DRUGS, BREASTFEEDING AND SMOKING. THE INTERACTIONS BETWEEN DIETARY NUTRIENTS AND INTESTINAL IMMUNITY ARE COMPLEX. THERE IS A COMPELLING ARGUMENT FOR ENVIRONMENTAL FACTORS SUCH AS DIET PLAYING A ROLE IN THE CAUSE AND COURSE OF IBD, GIVEN THAT THREE IMPORTANT FACTORS IN THE PATHOGENESIS OF IBD CAN BE MODULATED AND CONTROLLED BY DIET: INTESTINAL MICROBIOTA, THE IMMUNE SYSTEM AND EPITHELIAL BARRIER FUNCTION. THE AIM OF THIS REVIEW IS TO SUMMARIZE THE EPIDEMIOLOGICAL FINDINGS REGARDING DIET AND TO FOCUS ON THE EFFECTS THAT NUTRIENTS EXERT ON THE INTESTINAL MUCOSA-MICROBIOTA-PERMEABILITY INTERACTION. THE NATURE OF THESE INTERACTIONS IN IBD IS INFLUENCED BY ALTERATIONS IN THE NUTRITIONAL METABOLISM OF THE GUT MICROBIOTA AND HOST CELLS THAT CAN INFLUENCE THE OUTCOME OF NUTRITIONAL INTERVENTION. A BETTER UNDERSTANDING OF DIET-HOST-MICROBIOTA INTERACTIONS IS ESSENTIAL FOR UNRAVELLING THE COMPLEX MOLECULAR BASIS OF EPIGENETIC, GENETIC AND ENVIRONMENTAL INTERACTIONS UNDERLYING IBD PATHOGENESIS AS WELL AS FOR OFFERING NEW THERAPEUTIC APPROACHES FOR THE TREATMENT OF IBD. 2019 8 1404 20 DIETARY COMPOSITION AND EFFECTS IN INFLAMMATORY BOWEL DISEASE. DRAMATIC CHANGES IN THE ENVIRONMENT AND HUMAN LIFESTYLE HAVE BEEN ASSOCIATED WITH THE RISE OF VARIOUS CHRONIC COMPLEX DISEASES, SUCH AS INFLAMMATORY BOWEL DISEASE (IBD). A DYSBIOTIC GUT MICROBIOTA HAS BEEN PROPOSED AS A CRUCIAL PATHOGENIC ELEMENT, CONTRIBUTING TO IMMUNE IMBALANCES AND FOSTERING A PROINFLAMMATORY MILIEU, WHICH MAY BE ASSOCIATED WITH DISEASE RELAPSES OR EVEN THE INITIATION OF IBD. IN ADDITION TO REPRESENTING IMPORTANT REGULATORS OF THE MUCOSAL IMMUNITY AND THE COMPOSITION OF THE GUT MICROBIOTA, FOOD COMPONENTS HAVE BEEN SHOWN TO BE POTENTIAL ENVIRONMENTAL TRIGGERS OF EPIGENETIC MODIFICATIONS. IN THE CONTEXT OF CHRONIC INTESTINAL INFLAMMATION, DIETARY HABITS AND SPECIFIC FOOD COMPONENTS HAVE BEEN IMPLICATED AS IMPORTANT MODULATORS OF EPIGENETIC MECHANISMS, INCLUDING DNA METHYLATION, WHICH MAY PREDISPOSE A PERSON TO THE INCREASED RISK OF THE INITIATION AND EVOLUTION OF IBD. THIS REVIEW PROVIDES NOVEL INSIGHTS ABOUT HOW DIETARY FACTORS MAY INTERACT WITH THE INTESTINAL MUCOSA AND MODULATE IMMUNE HOMEOSTASIS BY SHAPING THE INTESTINAL ECOSYSTEM, AS WELL AS THE POTENTIAL INFLUENCE OF DIET IN THE ETIOPATHOGENESIS AND MANAGEMENT OF IBD. 2019 9 5528 19 RNA MODIFICATION IN INFLAMMATORY BOWEL DISEASES. INFLAMMATORY BOWEL DISEASE (IBD) IS A CHRONIC INFLAMMATORY DISORDER CHARACTERIZED BY DAMAGE TO THE INTESTINAL MUCOSA, WHICH IS CAUSED BY A COMBINATION OF FACTORS. THESE INCLUDE GENETIC AND EPIGENETIC ALTERATIONS, ENVIRONMENTAL INFLUENCE, MICROORGANISM INTERACTIONS, AND IMMUNE CONDITIONS. SOME POPULATIONS WITH IBD SHOW A CANCER-PRONE PHENOTYPE. RECENT STUDIES HAVE PROVIDED INSIGHT INTO THE INVOLVEMENT OF RNA MODIFICATIONS IN THE SPECIFIC PATHOGENESIS OF IBD THROUGH REGULATION OF RNA BIOLOGY IN EPITHELIAL AND IMMUNE CELLS. STUDIES OF SEVERAL RNA MODIFICATION-TARGETING REAGENTS HAVE SHOWN PREFERABLE OUTCOMES IN PATIENTS WITH COLITIS. HERE, WE NOTE A NEW AWARENESS OF RNA MODIFICATION IN THE TARGETING OF IBD AND RELATED DISEASES, WHICH WILL CONTRIBUTE TO EARLY DIAGNOSIS, DISEASE MONITORING, AND POSSIBLE CONTROL BY INNOVATIVE THERAPEUTIC APPROACHES. 2022 10 3692 18 INFLAMMATORY BOWEL DISEASES: THE ROLE OF GUT MICROBIOTA. INFLAMMATORY BOWEL DISEASES (IBD) ARE CHRONIC MULTIFACTORIAL DISEASES CHARACTERIZED BY PARTIALLY UNCLEAR PATHOGENIC MECHANISMS INCLUDING CHANGES IN INTESTINAL MICROBIOTA. DESPITE THE MICROBIOTA, ALTERATION IS WELL ESTABLISHED IN IBD PATIENTS, AS REPORTED BY 16RNA SEQUENCING ANALYSIS, AN IMPORTANT GOAL IS TO DEFINE IF IT IS JUST A CONSEQUENCE OF THE DISEASE PROGRESSION OR A TRIGGER FACTOR OF THE DISEASE ITSELF. TO DATE, GUT MICROBIOTA COMPOSITION AND GUT MICROBIOTA-RELATED METABOLITES SEEM TO AFFECT THE HOST HEALTHY STATE BOTH BY MODULATING METABOLIC PATHWAYS OR ACTING ON THE EXPRESSION OF DIFFERENT GENES THROUGH EPIGENETIC EFFECTS. BECAUSE OF THIS, IT HAS BEEN SUGGESTED THAT INTESTINAL MICROBIOTA MIGHT REPRESENT A PROMISING THERAPEUTIC TARGET FOR IBD PATIENTS. THE AIM OF THIS REVIEW IS TO SUMMARIZE BOTH THE MOST RECENT ACQUISITIONS IN THE FIELD OF GUT MICROBIOTA AND ITS INVOLVEMENT IN INTESTINAL INFLAMMATION TOGETHER WITH THE AVAILABLE STRATEGIES FOR THE MODULATION OF MICROBIOTA, SUCH AS PREBIOTICS AND/OR PROBIOTICS ADMINISTRATION OR FECAL MICROBIOTA TRANSPLANTATION. 2020 11 2601 20 EPIGENETICS, DNA ORGANIZATION, AND INFLAMMATORY BOWEL DISEASE. INFLAMMATORY BOWEL DISEASES (IBDS) ARE CHRONIC INFLAMMATORY DISORDERS AFFECTING THE GASTROINTESTINAL TRACT. THE INCIDENCE OF IBD IS INCREASING, WITH MORE CASES OCCURRING IN DEVELOPED COUNTRIES. MULTIPLE FACTORS SUCH AS GENETICS, ENVIRONMENTAL CHANGES, GUT MICROBIOTA, AND IMMUNE ABNORMALITIES HAVE BEEN ASSOCIATED WITH DEVELOPMENT OF IBD. IN RECENT YEARS, IT HAS BECOME INCREASINGLY APPARENT THAT EPIGENETIC MODIFICATIONS OF CHROMATIN AND THE MANNER IN WHICH CHROMATIN IS ORGANIZED IN THE NUCLEUS ARE ADDITIONALLY IMPORTANT ELEMENTS THAT CAN INFLUENCE RESPONSES INDUCED BY THE FACTORS DESCRIBED ABOVE, AND MAY THEREFORE CONTRIBUTE TO THE ONSET AND PATHOGENESIS OF IBD. EPIGENETICS AND CHROMATIN ORGANIZATION REGULATE DIVERSE FUNCTIONS THAT INCLUDE MAINTENANCE OF HOMEOSTASIS IN THE INTESTINAL EPITHELIUM, THE DEVELOPMENT AND DIFFERENTIATION OF IMMUNE CELLS, AND MODULATION OF RESPONSES GENERATED BY THE IMMUNE SYSTEM TO DEFEND AGAINST POTENTIAL PATHOGENS. FURTHERMORE, CHANGES IN EPIGENETIC CHROMATIN MARKS AND IN CHROMATIN ORGANIZATION HAVE NOW BEEN LINKED TO DIFFERENTIAL GENE EXPRESSION IN IBD PATIENT CELLS. ALTHOUGH DIRECT EVIDENCE FOR A ROLE OF HISTONE MODIFICATIONS IN IBD IS CURRENTLY VERY LIMITED, IN THIS REVIEW, WE SUMMARIZE THE LINKS BETWEEN VARIOUS EPIGENETIC MODIFICATIONS, THE PROTEINS THAT CATALYZE OR RECOGNIZE THESE MODIFICATIONS, AND THE DEVELOPMENT OR PROGRESSION OF IBD IN HUMAN AND EXPERIMENTAL IBD. WE ALSO DISCUSS HOW EPIGENETICS INFLUENCE THE ORGANIZATION OF DNA CONTACTS TO REGULATE GENE EXPRESSION AND THE IMPLICATIONS THIS MAY HAVE FOR DIAGNOSING AND TREATING IBD. 2019 12 3920 18 LINKING IMMUNITY, EPIGENETICS, AND CANCER IN INFLAMMATORY BOWEL DISEASE. MOST OF WHAT IS KNOWN ABOUT THE PATHOGENESIS OF INFLAMMATORY BOWEL DISEASE (IBD) PERTAINS TO COMPLEX INTERPLAY BETWEEN HOST GENETICS, IMMUNITY, AND ENVIRONMENTAL FACTORS. EPIGENETIC MODIFICATIONS PLAY PIVOTAL ROLES IN INTESTINAL IMMUNITY AND MUCOSAL HOMEOSTASIS AS WELL AS MEDIATING GENE-ENVIRONMENT INTERACTIONS. IN THIS ARTICLE, WE PROVIDE A HISTORICAL ACCOUNT OF EPIGENETIC RESEARCH EITHER DIRECTLY RELATED OR PERTINENT TO THE PATHOGENESIS AND MANAGEMENT OF IBD. WE FURTHER COLLATE EMERGING EVIDENCE SUPPORTING ROLES FOR EPIGENETIC MECHANISMS IN RELEVANT ASPECTS OF IBD BIOLOGY, INCLUDING DEREGULATED IMMUNITY, HOST-PATHOGEN RECOGNITION AND MUCOSAL INTEGRITY. FINALLY, WE HIGHLIGHT KEY EPIGENETIC MECHANISMS THAT LINK CHRONIC INFLAMMATION TO SPECIFIC IBD COMORBIDITIES, INCLUDING COLITIS-ASSOCIATED CANCER AND DISCUSS THEIR POTENTIAL UTILITY AS NOVEL BIOMARKERS OR PHARMACOLOGIC TARGETS IN IBD THERAPY. 2014 13 2875 15 FUNCTIONAL ROLE AND THERAPEUTIC TARGETING OF MICRORNAS IN INFLAMMATORY BOWEL DISEASE. INFLAMMATORY BOWEL DISEASES (IBD) ARE CHRONIC INFLAMMATORY GASTROINTESTINAL DISEASES, PRIMARILY CONSISTING OF ULCERATIVE COLITIS AND CROHN'S DISEASE. THE COMPLEX NATURE OF THE DISEASE, AS WELL AS THE LIMITED THERAPEUTIC OPTIONS CHARACTERIZED BY LOW EFFICIENCY AND MAJOR SIDE EFFECTS, HIGHLIGHTS THE IMPORTANCE OF DEVELOPING NOVEL STRATEGIES OF THERAPEUTIC INTERVENTION IN IBD. SUSCEPTIBILITY LOCI RELATED TO IBD ARE PRESENT ONLY IN A SMALL PERCENTAGE OF IBD PATIENTS, IMPLYING THAT EPIGENETIC MODIFICATIONS COULD INFLUENCE THE PATHOGENESIS OF THE DISEASE. MICRORNAS (MIRNAS) ARE SMALL NONCODING RNAS THAT REGULATE MULTIPLE MOLECULAR PATHWAYS INVOLVED IN IBD PATHOBIOLOGY. MIRNA INHIBITORS TARGETING THE IBD-ACTIVATED MIRNAS COULD HAVE THERAPEUTIC VALUE FOR IBD PATIENTS. THIS REVIEW PROVIDES AN OVERVIEW OF THE RECENT ADVANCES IN MIRNA BIOLOGY RELATED TO IBD PATHOGENESIS AND THE PHARMACOLOGICAL DEVELOPMENT OF MIRNA-BASED THERAPEUTICS. 2018 14 4365 19 MIRNA MOLECULES-LATE BREAKING TREATMENT FOR INFLAMMATORY BOWEL DISEASES? MICRORNAS (MIRNAS) ARE A GROUP OF NON-CODING RNAS THAT PLAY A CRITICAL ROLE IN REGULATING EPIGENETIC MECHANISMS IN INFLAMMATION-RELATED DISEASES. INFLAMMATORY BOWEL DISEASES (IBDS), WHICH PRIMARILY INCLUDE ULCERATIVE COLITIS (UC) AND CROHN'S DISEASE (CD), ARE CHARACTERIZED BY CHRONIC RECURRENT INFLAMMATION OF INTESTINAL TISSUES. DUE TO THE MULTIFACTORIAL ETIOLOGY OF THESE DISEASES, THE DEVELOPMENT OF INNOVATIVE TREATMENT STRATEGIES THAT CAN EFFECTIVELY MAINTAIN REMISSION AND ALLEVIATE DISEASE SYMPTOMS IS A MAJOR CHALLENGE. IN RECENT YEARS, EVIDENCE FOR THE REGULATORY ROLE OF MIRNAS IN THE PATHOGENETIC MECHANISMS OF VARIOUS DISEASES, INCLUDING IBD, HAS BEEN ACCUMULATING. IN LIGHT OF THESE FINDINGS, MIRNAS REPRESENT POTENTIAL INNOVATIVE CANDIDATES FOR THERAPEUTIC APPLICATION IN IBD. IN THIS REVIEW, WE DISCUSS RECENT FINDINGS ON THE ROLE OF MIRNAS IN REGULATING INFLAMMATORY RESPONSES, MAINTAINING INTESTINAL BARRIER INTEGRITY, AND DEVELOPING FIBROSIS IN CLINICAL AND EXPERIMENTAL IBD. THE FOCUS IS ON THE EXISTING LITERATURE, INDICATING POTENTIAL THERAPEUTIC APPLICATION OF MIRNAS IN BOTH PRECLINICAL EXPERIMENTAL IBD MODELS AND TRANSLATIONAL DATA IN THE CONTEXT OF CLINICAL IBD. TO DATE, A LARGE AND DIVERSE DATA SET, WHICH IS GROWING RAPIDLY, SUPPORTS THE POTENTIAL USE OF MIRNA-BASED THERAPIES IN CLINICAL PRACTICE, ALTHOUGH MANY QUESTIONS REMAIN UNANSWERED. 2023 15 3029 23 GENETICS OF INFLAMMATORY BOWEL DISEASES: A COMPARISON BETWEEN WESTERN AND EASTERN PERSPECTIVES. INFLAMMATORY BOWEL DISEASE (IBD) IS A CHRONIC RELAPSING INTESTINAL INFLAMMATORY DISORDER WITH UNIDENTIFIED CAUSES. CURRENTLY, STUDIES INDICATE THAT IBD RESULTS FROM A COMPLEX INTERPLAY BETWEEN VARIOUS GENETIC AND ENVIRONMENTAL FACTORS THAT PRODUCE INTESTINAL INFLAMMATION. HOWEVER, THESE FACTORS MAY DIFFER FOR ASIANS AND CAUCASIANS. THUS, DIFFERENCES IN EPIDEMIOLOGY, GENETIC VARIANTS, AND CLINICAL PHENOTYPES OF IBD HAVE BEEN OBSERVED BETWEEN THE TWO POPULATIONS. UNDERSTANDING THE DISCREPANCIES BETWEEN DATA FROM POPULATIONS WITH DIFFERENT GENETIC BACKGROUNDS AND ENVIRONMENTAL FACTORS MAY REVEAL FUNDAMENTAL ASPECTS OF IBD PATHOGENESIS. ACCORDINGLY, THIS REVIEW WILL SUMMARIZE THE CURRENT KNOWLEDGE OF IBD GENETICS STUDIED IN ASIAN COUNTRIES AND COMPARE IT WITH THAT FROM WESTERN COUNTRIES, WITH SPECIAL FOCUS ON INNATE BACTERIAL SENSING, AUTOPHAGY, AND THE INTERLEUKIN-23 RECEPTOR-T HELPER CELL 17 PATHWAY. THE EPIGENETIC NATURE OF IBD PATHOGENESIS AS WELL AS THE PHARMACOGENETICS RELATED TO THE USE OF IMMUNOMODULATORS WILL ALSO BE BRIEFLY COVERED. 2013 16 2368 17 EPIGENETIC REGULATION OF T HELPER CELLS AND INTESTINAL PATHOGENICITY. INFLAMMATORY BOWEL DISEASES (IBDS) ARE CHARACTERIZED BY RELAPSING AND REMITTING CHRONIC INTESTINAL INFLAMMATION. PREVIOUS STUDIES HAVE DEMONSTRATED THE CONTRIBUTIONS OF GENETIC BACKGROUND, ENVIRONMENTAL FACTORS (FOOD, MICROBIOTA, USE OF ANTIBIOTICS), AND HOST IMMUNITY IN THE DEVELOPMENT OF IBDS. MORE THAN 200 GENES HAVE BEEN SHOWN TO INFLUENCE IBD SUSCEPTIBILITY, MOST OF WHICH ARE INVOLVED IN IMMUNITY. THE VERTEBRATE IMMUNE SYSTEM COMPRISES A COMPLEX NETWORK OF INNATE AND ADAPTIVE IMMUNE CELLS THAT PROTECT THE HOST FROM INFECTION AND CANCER. DYSREGULATION OF THE MUTUALISTIC RELATIONSHIP BETWEEN THE IMMUNE SYSTEM AND THE GUT ENVIRONMENT RESULTS IN IBD. CONSIDERING THE FUNDAMENTAL ROLE OF EPIGENETIC REGULATION IN IMMUNE CELLS, EPIGENETIC MECHANISMS, PARTICULARLY IN T HELPER (TH) CELLS, MAY PLAY A MAJOR ROLE IN THE COMPLEX REGULATION OF MUCOSAL IMMUNITY. EPIGENETIC REGULATION AND DYSREGULATION OF TH CELLS ARE INVOLVED IN THE MAINTENANCE OF INTESTINAL HOMEOSTASIS AND ITS BREAKDOWN IN IBD. 2019 17 2027 23 EPIGENETIC CHANGES IN CHRONIC INFLAMMATORY DISEASES. THE NUMBER OF PEOPLE DIAGNOSED WITH CHRONIC INFLAMMATORY DISEASES HAS INCREASED NOTEWORTHY IN THE LAST 40 YEARS. SPONDYLOARTHRITIS (SPA), INFLAMMATORY BOWEL DISEASES (IBD), AND PSORIASIS ARE THE MOST FREQUENT CHRONIC INFLAMMATORY DISEASES, RESULTING FROM A COMBINATION OF GENETIC PREDISPOSITION AND ENVIRONMENTAL FACTORS. EPIGENETIC MODIFICATIONS INCLUDE DNA METHYLATION, HISTONE MODIFICATIONS, AND SMALL AND LONG NONCODING RNAS. THEY ARE INFLUENCED BY ENVIRONMENTAL EXPOSURE, LIFE-STYLE, AND AGING AND HAVE RECENTLY BEEN SHOWN TO BE ALTERED IN MANY COMPLEX DISEASES INCLUDING INFLAMMATORY DISEASES. WHILE EPIGENETIC MODIFICATIONS HAVE BEEN WELL CHARACTERIZED IN OTHER DISEASES SUCH AS CANCER AND AUTOIMMUNE DISEASES, KNOWLEDGE ON CHANGES IN INFLAMMATORY DISEASES IS LAGGING BEHIND WITH SOME DISEASE-SPECIFIC DIFFERENCES. WHILE THE DNA METHYLATION PROFILE OF DIFFERENT CELL TYPES IN PATIENTS WITH IBD HAS BEEN RELATIVELY WELL DESCRIBED, LESS IS KNOWN ON CHANGES IMPLICATED IN PSORIASIS, AND NO SYSTEMATIC GENOME-WIDE STUDIES HAVE SO FAR BEEN PERFORMED IN SPA. IN THIS CHAPTER, WE REVIEW IN DETAIL THE REPORTED CHANGES IN PATTERNS OF DNA METHYLATION AND POSTTRANSLATIONAL HISTONE MODIFICATIONS IN CHRONIC INFLAMMATORY DISEASES HIGHLIGHTING POTENTIAL CONNECTIONS BETWEEN DISEASE-ASSOCIATED PATHOPHYSIOLOGICAL CHANGES SUCH AS THE DYSBIOSIS OF THE MICROBIOME OR GENETIC VARIATIONS ASSOCIATED WITH DISEASE SUSCEPTIBILITY AND THE EPIGENOME. WE ALSO DISCUSS IMPORTANT PARAMETERS OF MEANINGFUL EPIGENETIC STUDIES SUCH AS THE USE OF WELL DEFINED, DISEASE-RELEVANT CELL POPULATIONS, AND ELUDE ON THE POTENTIAL FUTURE OF ENGINEERING OF THE EPIGENOME IN INFLAMMATORY DISEASES. 2017 18 4274 24 MICROBIOTA IN INFLAMMATORY BOWEL DISEASE PATHOGENESIS AND THERAPY: IS IT ALL ABOUT DIET? INFLAMMATORY BOWEL DISEASE (IBD), INCLUDING ULCERATIVE COLITIS, CROHN'S DISEASE, AND UNCLASSIFIED IBD, CONTINUES TO CAUSE SIGNIFICANT MORBIDITY. WHILE ITS INCIDENCE IS INCREASING, NO CLEAR ETIOLOGY AND NO CURE HAVE YET BEEN DISCOVERED. RECENT FINDINGS SUGGEST THAT IBD MAY HAVE A MULTIFACTORIAL ETIOLOGY, WHERE COMPLEX INTERACTIONS BETWEEN GENETICS, EPIGENETICS, ENVIRONMENTAL FACTORS (INCLUDING DIET BUT ALSO INFECTIONS, ANTIBIOTICS, AND SANITATION), AND HOST IMMUNE SYSTEM LEAD TO ABNORMAL IMMUNE RESPONSES AND CHRONIC INFLAMMATION. OVER THE PAST YEARS, THE ROLE OF ALTERED GUT MICROBIOTA (IN BOTH COMPOSITION AND FUNCTION) IN IBD PATHOGENESIS HAS EMERGED AS AN OUTSTANDING AREA OF INTEREST. ACCORDING TO NEW FINDINGS, GUT DYSBIOSIS MAY APPEAR AS A KEY ELEMENT IN INITIATION OF INFLAMMATION IN IBD AND ITS COMPLICATIONS. MOREOVER, COMPLEX METAGENOMIC STUDIES PROVIDE POSSIBILITIES TO DISTINGUISH BETWEEN IBD TYPES AND APPRECIATE SEVERITY AND PROGNOSIS OF THE DISEASE, AS WELL AS RESPONSE TO THERAPY. THIS REVIEW PROVIDES AN UPDATED KNOWLEDGE OF RECENT FINDINGS LINKING ALTERED BACTERIAL COMPOSITION AND FUNCTIONS, VIRUSES, AND FUNGI TO IBD PATHOGENESIS. IT ALSO HIGHLIGHTS THE COMPLEX GENETIC, EPIGENETIC, IMMUNE, AND MICROBIAL INTERACTIONS IN RELATION TO ENVIRONMENTAL FACTORS (INCLUDING DIET). WE OVERVIEW THE ACTUAL OPTIONS TO MANIPULATE THE ALTERED MICROBIOTA, SUCH AS MODIFIED DIET, PROBIOTICS, PREBIOTICS, SYNBIOTICS, ANTIBIOTICS, AND FECAL TRANSPLANTATION. FUTURE POSSIBLE THERAPIES ARE ALSO INCLUDED. TARGETING ALTERED MICROBIOTA COULD BE THE NEXT THERAPEUTIC PERSONALIZED APPROACH, BUT MORE RESEARCH AND WELL-DESIGNED COMPARATIVE PROSPECTIVE STUDIES ARE REQUIRED TO FORMULATE ADEQUATE DIRECTIONS FOR PREVENTION AND THERAPY. 2015 19 3681 22 INFLAMMATION, DNA METHYLATION AND COLITIS-ASSOCIATED CANCER. INFLAMMATION CAN RESULT FROM A RANGE OF SOURCES INCLUDING MICROBIAL INFECTIONS, EXPOSURE TO ALLERGENS AND TOXIC CHEMICALS, AUTOIMMUNE DISEASE AND OBESITY. A WELL-BALANCED IMMUNE RESPONSE CAN BE ANTI-TUMORIGENIC; HOWEVER, A SUSTAINED OR CHRONIC INFLAMMATORY RESPONSE IS GENERALLY HARMFUL AS THE IMMUNE RESPONSE BECOMES DISTORTED. A CAUSAL LINK BETWEEN CHRONIC INFLAMMATION AND CANCER IS NOW WELL ACCEPTED AND MANY CHRONICALLY INFLAMED ORGANS OF THE GASTROINTESTINAL TRACT SHOW THIS ASSOCIATION. FOR EXAMPLE, PATIENTS WITH INFLAMMATORY BOWEL DISEASE (IBD), INCLUDING BOTH ULCERATIVE COLITIS AND CROHN'S DISEASE, HAVE A 2- TO 3-FOLD GREATER LIFETIME RISK OF DEVELOPING COLORECTAL CANCER COMPARED WITH THE GENERAL POPULATION. THE DEVELOPMENT OF COLITIS-ASSOCIATED CANCER (CAC) IS THOUGHT TO BE MULTIFACETED AND IS PROBABLY DUE TO A COMBINATION OF GENETIC FACTORS, EPIGENETIC FACTORS AND THE DURATION, EXTENT AND SEVERITY OF DISEASE. RECENTLY, EPIGENETIC ALTERATIONS, IN PARTICULAR ALTERATIONS IN DNA METHYLATION, HAVE BEEN OBSERVED DURING INFLAMMATION AND INFLAMMATION-ASSOCIATED CARCINOGENESIS. THE MEDIATORS OF THIS, THE SIGNIFICANCE OF THESE CHANGES IN DNA METHYLATION AND THE EFFECT THIS HAS ON GENE EXPRESSION AND THE MALIGNANT TRANSFORMATION OF THE EPITHELIAL CELLS DURING IBD AND CAC ARE DISCUSSED IN THIS REVIEW. THE RECENT ADVANCES IN TECHNOLOGIES TO STUDY GENOME-WIDE DNA METHYLATION AND THE THERAPEUTIC POTENTIAL OF UNDERSTANDING THESE MOLECULAR MECHANISMS ARE ALSO HIGHLIGHTED. 2012 20 6353 18 THE ROLE OF GENETIC AND EPIGENETIC REGULATION IN INTESTINAL FIBROSIS IN INFLAMMATORY BOWEL DISEASE: A DESCENDING PROCESS OR A PROGRAMMED CONSEQUENCE? INFLAMMATORY BOWEL DISEASES (IBDS) ARE A GROUP OF CHRONIC DISEASES CHARACTERIZED BY RECURRING PERIODS OF EXACERBATION AND REMISSION. FIBROSIS OF THE INTESTINE IS ONE OF THE MOST COMMON COMPLICATIONS OF IBD. BASED ON CURRENT ANALYSES, IT IS EVIDENT THAT GENETIC FACTORS AND MECHANISMS, AS WELL AS EPIGENETIC FACTORS, PLAY A ROLE IN THE INDUCTION AND PROGRESSION OF INTESTINAL FIBROSIS IN IBD. KEY GENETIC FACTORS AND MECHANISMS THAT APPEAR TO BE SIGNIFICANT INCLUDE NOD2, TGF-BETA, TLRS, IL23R, AND ATG16L1. DEOXYRIBONUCLEIC ACID (DNA) METHYLATION, HISTONE MODIFICATION, AND RIBONUCLEIC ACID (RNA) INTERFERENCE ARE THE PRIMARY EPIGENETIC MECHANISMS. GENETIC AND EPIGENETIC MECHANISMS, WHICH SEEM TO BE IMPORTANT IN THE PATHOPHYSIOLOGY AND PROGRESSION OF IBD, MAY POTENTIALLY BE USED IN TARGETED THERAPY IN THE FUTURE. THEREFORE, THE AIM OF THIS STUDY WAS TO GATHER AND DISCUSS SELECTED MECHANISMS AND GENETIC FACTORS, AS WELL AS EPIGENETIC FACTORS. 2023